Liquid centrifuge core



1966 E. F. BABELAY ETAL 3,288,360

LIQUID CENTRIFUGE CORE Filed June 16, 1964 INVENTORS.

Edwin F. Babe/0y BY Huberf P. Barringer ATTORNEY United States Patent3,288,360 LIQUID CENTRIFUGE CORE Edwin F. Babelay, Knoxville, and HubertP. Barringer,

Oak Ridge, Tenn., assignors to the United States of America asrepresented by the United States Atomic Energy Commission Filed June 16,1964, Ser. No. 375,681 Claims. (Cl. 233-22) The present inventionrelates to liquid centrifuges generally and more specifically to animproved core for a liquid centrifuge bowl.

A basic problem encountered in the development of the liquid zonal ordensity-gradient centrifuge has been to accelerate the liquid gradientto operational speed with a minimum of mixing, and to recover thegradient at the end of the centrifugation with a high resolution inseparation between the zones of differing density or dilferentsedimentation coefficients. Another problem has been that of providingrotor stability during high speed operation. Instability at the highspeeds of interest not only causes mixing but may also result in thedestruction of the centrifuge.

It is accordingly an object of this invention to provide a liquidcentrifuge core characterized by a high resolution of the isopycnic andrate zonal separations.

Another object of this invention is to provide a rotor corecharacterized by high resolution of the zonal separations with a smallnumber of rotor partitions.

Another object is to provide a core having a high critical vibrationalfrequency.

Other objects of the invention will become apparent from an examinationof the following description of the invention and the appended drawingswherein:

FIG. 1 is a vertical sectional view showing an embodiment of the subjectimproved core design mounted within a liquid centrifuge bowl.

FIG. 2 is a horizontal section of the centrifuge bowl and improved coreof FIG. 1.

FIG. 3 is a cross sectional view of the subject improved core designillustrating the movement of a gradient band toward the core withdrawalpoint.

In accordance with the present invention, an improved core is providedfor a liquid centrifuge of the type incorporating a vertically orientedcylindrical bowl which is rotated about its axis. The improved corecomprises a right regular prismatic body having a plurality oflongitudinally extending flat faces which is centrally disposed in thebowl. Vanes or septa extend outwardly from the prismatic body alongplanes bisecting each included angle at the periphery of the body. Eachof the fiat faces is equally divided by a longitudinally extendinggroove of varying depth, the groove having its greatest depth at awithdrawal port which communicates with a conduit passage disposedwithin the prismatic body and communicating with an end face thereof.

To facilitate an understanding of the invention, reference is made toFIGS. 1 and 2 wherein a preferred embodiment of the subject invention isillustrated. A rotor bowl 1 and rotor end caps 2 and 2' define aright-cylindrical cavity in which a core 3 according to the subjectinvention is disposed. As can be seen most readily in FIG. 2, core 3comprises a central portion 4 of square crosssection, having equallyspaced, integral vanes or septa 5 extending radially from the cornersthereof. Withdrawal grooves '6, of varying depth cent-rally spaced onthe flat faces 7 of central portion 4, extend axially along the faces towithdrawal ports 8. The grooves 6 have their greatest depth at thewithdrawal ports which communicate with a tubular passageway 9 disposedaxially within central portion 4 of core 3 and extending to an end facethereof. The core 3 is supported centrally inside bowl 1 by means "iceof stud and recess systems 10 and 11 between core 3 and top and bottomend caps 2 and 2' respectively.

Although the central portion 4 of core 3 has a square cross-section inthe preferred embodiment illustrated'in the drawings and describedabove, other right prismatic cent-r al portions having a greater or lessnumber of flat side faces may be used. In general, however, the centralportion which operates satisfactorily with the least number of faces ismost desirable as it will be the simplest and easiest core to fabricate.A secondary benefit also results in that with fewer septa a largerpercentage of the rotor volume is available to the fluid beingcentrifuged, thereby enabling the fluid volume and centrifuge capacityto be correspondingly increased.

In a typical operation, an impure virus sample was separated fromassociated foreign proteins and other undesirable materials containedtherein using the hereinbefore described centrifuge system.

Core 3 and a rotor bowl 1, having a 4 inch internal diameter, wereassembled and rotated at 5000 r.p.m. While rotating at this speed, aliquid batch having a gradually increasing density was admitted at theinner rotor periphery through tubular passageway 12 which runs throughend cap 2. After the density gradient was in the rotor, additional densefluid (concentrated sucrose), termed the cushion was pumped in throughpassageway 12 until the light end of the gradient began to flow out thecenter passageway 9 within core 3 indicating that the rotor wascompletely full. At that point the sample layer was introduced throughthe center passageway 9, reversing the direction of fluid flow throughthe rotor and causing part of the cushion to flow back out through theedge passageway 12. In order to form the sample layer into a thin zone,an overlay of fluid lighter than the sample layer was introduced afterthe sample. This forced the sample layer out into the rotor chamberclear of the center core. The connection to the rotor edge throughpassageway 12 was then closed, and the center passageway attached to areservoir of water to allow a small volume of fluid to flow into therotor during acceleration to compensate for rotor expansion.

The speed of the rotor was then increased to 40,000 r.p.m. for a periodsufficient for the particulate matter in the virus sample to sediment inthe gradient provided by the liquid batch previously inserted into therotor.

The rotor speed was then reduced to 5000 r.p.m. and the sedimentcomponents of the virus sample removed from the bowl through innerpassageway 9 by admitting a dense sucrose solution to the rotor edgethrough passageway 12, thereby driving the lower density zones intowithdrawal grooves 6, ports 8 and passageway 9.

The entire gradient, as it was recovered, was passed through anultraviolet absorption monitoring system, and into fraction collectortubes.

FIG. 3 illustrates schematically the withdrawal of a single zone or band13 of particulate matter as it is brought increasingly close to the core'3 as shown in quadrants I through IV. Note that the flat faces 7 havethe effect of increasing the width of the band as it approaches thewithdrawal groove and acts to funnel the band into the withdrawalgroove. This effect is due to the fact that a flat surface cuts acrossthe density gradient which increases radially in a rotating centrifuge.The flat faces 7 are placed so that the withdrawal grooves 6 are locatedat the innermost radial position of the faces and therefore at the pointof least pressure and lowest density. The band being collected advancesalong the flat faces 7 from the higher pressure region where they joinwith the septa 5, to the withdrawal grooves 6 which are at the lowestpressure, radially-innermost point along each wall. The withdrawalgrooves 6 are varied in depth to a maximum depth at withdrawal ports 8so as to con- J tinue the path of decreasing pressure and densityinwardly to passageway 9.

ORNLr-3415, available from the OFrice' of Technical Services,Washington, D.C., describes an intermediate speed B-II zonal rotor inwhich the subject core may be used. This report was issued in connectionwith the Joint National Institutes of Health-Atomic Energy Conn missionZonal Centrifuge Development Program.

The above description of one form of the invention was offered forillustrative purposes only, and should not be interpreted in a limitingsense. It is intended that the invention be limited only 'by the claimsappended hereto.

What is claimed is:

1. A core for insertion into a cylindrical centrifuge bowl comprising:

(a) an elongated right prismatic body having at least three fiat sidefaces,

('b) radially extending fins affixed to said prismatic body along thelines of intersection of said side faces,

(c) a longitudinally extending inclined groove disposed centrally ineach of said side faces, and

(d) fluid conducting rneans communicating with the deepest point of eachof said grooves.

2. A core for insertion into a cylindrical centrifuge bowl comprising:

(a) an elongated right prismatic body having at least three flat sidefaces, each face defining first and second angles between it andrespective adjacent faces,

(b) radially extending fins bisecting each of said angles at eachintersection of two faces,

() an axially-extending passageway through said elongated prismaticbody,

((1) radially-extending ports each leading from said axial passageway toa point below a respective face midway between adjacent fins, and

(e) an inclined groove disposed centrally in each face and extendinglongitudinally in opposite directions from said port, said portscommunicating with the deepest point in each of said grooves.

3. A core for insertion into a cylindrical centrifuge bowl comprising:

(a) an elongated regular right prismatic body having at least three sidefaces,

(b) radially extending fins integrally affixed to said prismatic bodyalong the lines of intersection of said side faces,

(c) an axially extending passageway disposed centrally within saidprismatic body,

((1) a longitudinally extending inclined groove disposed centrally ineach of said side faces, and

(e) radially-extending ports leading from said axial passageway to thedeepest point of each of said inclined grooves.

4. A core for insertion into a cylindrical centrifuge bowl comprising:

(a) an elongated right prismatic body having four side faces,

(b) radially extending fins integrally afiixed to said prismatic bodyalong the intersections of said side faces, said fins coinciding withplanes passing diagonally through said prismatic body,

(0) an axially extending passageway disposed centrally within saidprismatic body,

(d) a longitudinally extending inclined groove disposed centrally ineach of said faces, and

(e) radially-extending ports leading from said axial passageway to thedeepest point of each of said inclined grooves.

5. A core for insertion into a cylindrical centrifuge bowl comprising:

(a) an elongated right prismatic body having a square cross section,

(b) radially extending fins equal in length to said prismatic bodyintegrally affixed to the corners of said body,

(c) an axially extending passageway disposed centrally within saidprismatic body,

((1) a longitudinally extending groove of increasing depth disposedcentrally in each side face of said prismatic body, and p (e)radially-extending ports leading from said axial passageway to thedeepest point of each of said grooves.

References Cited by the Examiner UNITED STATES PATENTS 2,563,550 8/1951Quist 233-21 3,168,474 2/1965 Stallman et al 233-33 3,195,809 7/1965Pickels et a1. 233-21 M. CARY NELSON, Primary Examiner.

HENRY T. KLINKSIEK, Atssistant Examiner.

1. A CORE FOR INSERTION INTO A CYLINDRICAL CENTRIFUGE BOWL COMPRISING:(A) AN ELONGATED RIGHT PRISMATIC BODY HAVING AT LEAST THREE FLAT SIDEFACES, (B) RADIALLY EXTENDING FINS AFFIXED TO SAID PRISMATIC BODY ALONGTHE LINES OF INTERSECTION OF SAID SIDE FACES, (C) A LONGITUDINALLYEXTENDING INCLINED GROOVE DISPOSED CENTRALLY IN EACH OF SAID SIDE FACES,AND (D) FLUID CONDUCTING MEANS COMMUNICATING WITH THE DEEPEST POINT OFEACH OF SAID GROOVES.